So I typically wash my Miata whenever it’s at my parents’ place. Scrub every reachable square inch of the body and wheels, vacuum and dust off the interior, and this time going one step further...

Cleaning up the black gunk around and under the gas door. This is the after picture, it was 100x worse and the entire area was covered in an ugly mold-like black substance. You can see traces of residue around the edges of the underside of the fuel door. I’m very satisfied with the results!